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# Ultrasound watch

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1. b)
Suggest, with reasons, a maximum duration for the ultrasound pulses used in this scanner. Assume that images are formed from boundaries between 2.0cm and 12cm from the transmitter.

This is a guided answer, i'm not really sure what to put in the gaps.

The shortest time between emitting a pulse and detecting its echo is for boundaries at .......... . The time for the return trip of a pulse to this boundary is "2.86x10-5"?. In order that the returning pulse cannot be confused with the emitted pulse, the maximum pulse duration must be "less"?

c)
Discuss whether details 0.5mm across can be imaged using ultrasound in the range 2 - 10MHz.
I've worked out the maximum wavelengths for each frequency, but im not sure where to go from there.
2. (Original post by znx)
b)
Suggest, with reasons, a maximum duration for the ultrasound pulses used in this scanner. Assume that images are formed from boundaries between 2.0cm and 12cm from the transmitter.

This is a guided answer, i'm not really sure what to put in the gaps.

The shortest time between emitting a pulse and detecting its echo is for boundaries at .......... . The time for the return trip of a pulse to this boundary is "2.86x10-5"?. In order that the returning pulse cannot be confused with the emitted pulse, the maximum pulse duration must be "less"?

c)
Discuss whether details 0.5mm across can be imaged using ultrasound in the range 2 - 10MHz.
I've worked out the maximum wavelengths for each frequency, but im not sure where to go from there.
one rule of thumb is you can't image detail finer than 1/2 wavelength...

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